The Co Down man was presented with the accolade by Fifty Shades of Grey author EL James at the ceremony on Tuesday night.
Dornan is set to portray the billionaire Christian Grey in the upcoming film version of the erotic best seller in February.
Belfast singer Van Morrison was also presented with a trophy after he won the Legend Award, while Ballymena actor Liam Neeson won the Editor's Special Award.
Another big winner at the star-studded event was Wolf of Wall Street star Jonah Hill, who took aim at his schoolboy love while accepting the style trophy from Bradley Cooper.
Hill said: "Emily, my first girlfriend... You broke my heart and left it shattered. It was really sad. I know you were young and love is wild and you grow apart, but I'm GQ International Man of the f**king Year!"
The twice Oscar-nominated star joined Colin Firth, Pharrell Williams, New Order, new Doctor Who Peter Capaldi, racing driver Lewis Hamilton and Paulo Nutini among the big style winners, while Johnny Depp presented punk veteran Iggy Pop with GQ's Icon Award.
And the women weren't left out - Kim Kardashian West, who was joined on the red carpet by her husband Kanye West, picked up the Woman of the Year prize in a custom-designed haute couture Ralph & Russo gown.
Reminding the world her full name is now Kim Kardashian West, the reality TV star said: "I want to thank GQ for making me Woman of the Year, and my husband for making me feel like woman of the year every day."
Among those handing over the top prizes at the ceremony were Lindsay Lohan, Bradley Cooper, Gerard Butler, Rita Ora, Cara Delevingne, Daisy Lowe, Bob Geldof and Pippa Middleton.
The full list of GQ Men of the Year Award winners:
Comedian of the Year: John Bishop
Editor's Special Award: Liam Neeson
Chef of the Year: Tom Kerridge
Designer of the Year: Christopher Bailey
International Man of the Year: Jonah Hill
Writer of the Year: Michael Lewis
Philanthropist of the Year: Tony Blair
Breakthrough Fashion Designers of the Year: Agi and Sam
TV Personality of the Year: Peter Capaldi
Innovator Award: Ewan Venters
Inspiration Award: New Order
Hugo Boss Most Stylish Man: Douglas Booth
Sportsman: Lewis Hamilton
Actor of the Year: Benedict Cumberbatch
Entrepreneur of the Year: Andre Balazs
Special Achievement: Paolo Nutini
Vertu Breakthrough Award: Jamie Dornan
Legend Award: Van Morrison
Solo Artist of the Year: Pharrell Williams
Leading Man of the Year: Colin Firth
Humanitarian of the Year: Ringo Starr
Woman of the Year: Kim Kardashian West
Icon Award: Iggy Pop